Download raw (1.9 KB)

%!PS-Adobe
%%BoundingBox: 30 200 650 400

% Sine wave drawing by Toby Thain (mailto:toby@telegraphics.com.au)
% - straight line approximation
% - simplistic Bezier curve fitting
% both governed by "step" parameter (radians)

%    Copyright (C) 2001-3 Toby Thain, toby@telegraphics.com.au
%
%    This program is free software; you can redistribute it and/or modify
%    it under the terms of the GNU General Public License as published by  
%    the Free Software Foundation; either version 2 of the License, or
%    (at your option) any later version.
%
%    This program is distributed in the hope that it will be useful,
%    but WITHOUT ANY WARRANTY; without even the implied warranty of
%    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%    GNU General Public License for more details.
%
%    You should have received a copy of the GNU General Public License  
%    along with this program; if not, write to the Free Software
%    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

0 setgray

/pi 3.14159265 def
/step pi 4 div def % length of each line/curve segment; radians
/curvelength 33 def % curve length in radians

/r2d { 180 pi div mul } def % radians to degrees (approx)
/f { r2d sin } def % function to plot
/f' { r2d cos } def % first derivative

/drawpolygon {
	0 dup f moveto
	step dup curvelength {  % loop parameters for straight lines (radian units)
		dup f lineto
	} for
} def

/drawcurve {
	0 6 60 {
		0 1 index f moveto
		/third step 3 div def
		%0 dup f moveto
		0 step curvelength {  % loop parameters for Bezier approximation
			/x exch def
			x third add   x f x f' third mul add 
			x step third sub add   x step add dup f exch f' third mul sub 
			x step add   dup f  
			curveto
		} for
		stroke
	} for
} def

% transformation of unit sine wave - x radians, y -1..1
50 300 translate
10 10 scale

0.1 setlinewidth
% drawpolygon .6 setgray stroke


%10 20 translate
%drawcurve 0 setgray stroke

drawcurve

showpage